I' ve been researching several different intakes -- ones that supposedly "require no tuning." Now I have read all about Maf scaling, the effects of distance between Maf and filter, IAT's, drifting fuel trims, and A/F ratio. Lastly, is knock. Manufacturers seem to be able to design out all negative aspects except knock. It has been proven that most intakes increase knock due to the effects of slightly leaner A/ F ratio. I'm not talking about 1-3 counts. More like 10-12 in the example I' ve seen. How do the intake manufactures expect us to deal with the increased knock without being tuned? I must be missing something... So my question is what intake causes the least knock? Currently I have the K&N, Afe/Takeda/New Usdm Greddy, and a Perrin inlet tube and Cosworth filter. What kind of knock have folks been seeing on the stock tune (based on model year)? Any help would be appreciated.

 

Do you have a link to said proof, if it happens to be on the web? TIA

 

I'm having trouble capturing links as I'm typing on my phone but please see the motoiq.com project evo x regarding testing of the K&N intake. The tuner, Naji, provides an evoscan image of the knock on that particular intake. In the comments section under the article he states all intakes require a tune either to prevent ltft drift and/or to reduce knock. Some intakes (K&N, Bardabe, and Injen specifically) keep the fuel trims in check but still cause knock, according to Naji. Also, on the socal evo site he tests many intakes and posts evoscan data regarding their performance in regards to fuel trims and knock. He mentions on average 5 degrees of timing must be pulled. His screen name is Looney Tunes.

 

IMO, the stock evo x high octane timing map is quite aggressive in the top end rpm range of the 180-220 load cells. the high octane fuel map on the other hand is quite rich.

when stock, this would have less top end knock due to gobs of fuel providing some detonation resistance.

add some bolt-ons to the stock tune and your afr will lean out, thus knock count can become more apparent. on the brightside, when adding bolt-ons you will be shifting to higher load cells where your timing begins to decrease.

either way... TUNE THE CAR!

 

I think you should get a few more opinions there. I have run an intake untuned and have a few friends ( one with an 08, one with an 11) that did the same for a pretty long while. 10-12 counts of knock would do some damage, and you would feel heavy timing pulled. We never had any problem though.

If you are going to get an intake and stay untuned though, I would suggest one that utilizes the stock MAF housing ( Cobb is grea for this) rather than one like Ets ( I believe ets changes the MAF housing)

 

I went with the ETS UICP, AFE Dry-Flow SRI, and Perrin Inlet. I'm still keeping the Cosworth Drop-in just in case and am sending the K&N back. The red looks ridiculous and I don't like how close the filter is to the Maf. I ran it pretty hard after it was all installed and filled it up with 93 and 2 gallons of 99 (cheap insurance) to give me 95 octane. It runs smooth, no CEL's, and I didn't hear any knock. Based on my research, it seems like you can expect a knock sum of 5-6 from an intake, a knock sum of 2-4 from a cat-back, and a knock sum of 5-6 (with a boost spike) from a downpipe/test pipe. Add it all together for a total knock sum of roughly 15 (ECU is pulling 5* of timing). Oh, and don't forget to add the knock you get when you are stock (0-5)...

 

If people are interested in this (and it comes up once every six months, it seems), the best thing to read first, IMO, is this thread on SoCalEvo: http://www.socalevo.net/forum/index.php?topic=83379.0

Of course, if we get serious with this discussion, I would expect the makers of some of the more popular intakes to come on and dispute what Naji (of Looney Tuning) posted, but that might be useful, as well.

edit: Between you and me, if I were the maker of an intake that has been shown to often push the LTFTs up to +10% or more, then I'd be offering the new values to enter into the tables to get it back near zero. I wouldn't force people to go to a tuner and re-invent the wheel every time. If I had a rough estimate of how to compensate for the changes when the intake was installed, I'd tell people what the values are. Of course, that would also involve admitting that the intake drove the LTFTs way up in the first place, which maybe said makers won't want to do in public.

 

Yes, Sir! That is one of the threads I've been mentioning, along with the Motoiq article. And, your last point is really the crux of me posting about this issue in the first place. How do we really know what we're getting? A shiny pipe that physically fits on the car... with POWA numbers from a dyno... If we knew the full picture, I'd be simple to identify and tune for. I used to be the international sales and marketing director for a *major* aftermarket exhaust company. We knew a lot of **** we didn't tell the customer but never held back info, or produced bogus parts, that would come back and bite both them and us. But, back to the intakes... These folks that have been running multiple bolt-ons without a tune seem to be right on the line of throwing a code and safe knock. Is it safe? I just don't think it's wise to let the stock ECU calibration handle that knock. I'm going to get tuned eventually, it just pisses me off that these manufacturers are not telling us the whole story... I wish Naji would post here and confirm my findings...

 

Oh, it's worse than that, IMO. Let's say you install an intake that will ultimately settle at something like +10% LTFT. [AEM airbox ... cough ... cough.] But you immediately dyno the car - without doing any tuning - before the LTFT settles. You might see a significant HP increase because the car is now running leaner at WOT. (I assume that we all know that the OE maps are too rich.) So the maker of said intake posts the HP gain, maybe even mentioning that this is without any tuning. And they are not lying, technically. The car really did make those gains. But not for long. After a bunch more 4-minute cycles, the LTFTs rise and at least some of the gains are gone. In other words, the actual gains aren't nearly as much as what you see for the first half hour.

 

So, I *figure* if my '11 has a stock knock sum of 2 (seems to be about average for stock tune on 92-93 octane) and my intake adds 6, that would put me around 8 counts with my setup. Hopefully, my 95 octane will quell a few of those counts, leaving me with 5. Which is about right in line with Naji's findings. Surely, this is a safe number...? I mean we're only talking about pulling a degree or two of timing and hopefully not having to hit the low octane map, right...?

 

Subbed... this should be interesting.

and.... I'd like to know what Naji sees with an aFe intake and how he reviews it.

 

this is the exact thread that I was looking for. I hope someone answers these very valid questions. I'm considering an intake but don't have the cash for the intake and tune right now.

 

Unfortunately, real world engine management and combustion doesn't work like that.

Rich

 

If John has 7 apples and gives Sarah 5 ink cartridges, how many pencils does that leave John with. Answer = Someone throws a wireless router at your face.

 

^^ lol!